The invention relates to a machine for laying up fabric to produce a laminate and is primarily concerned with the laying up of fabric to produce skins for aerofoils such as top and bottom skins for aircraft wings.
Fibre reinforced plastics materials, for example glass or carbon fibre composite materials, can be laid one upon the other in an uncured form to produce a laminate which is then cured to form the final article. Such a material can be produced by laying up tapes side by side as described in UK No 0 118 266 on a single tool and it will be appreciated that manufacture of large wing skins by such a method is a lengthy process.
The present invention is concerned with the production of laminates from pieces of fabric which will enable the laminates to be produced more quickly than hitherto.
According to the invention there is provided a machine for laying up fabric to produce laminates, comprising a forming station for receiving a piece of fabric, profiling means at the forming station for shaping the fabric, a plurality of lay-up stations and carrier means for carrying the shaped fabric from the forming station to one or other of the lay-up stations and laying it in position at the selected lay-up station to form part of a laminate at that station, the process being repeated to produce a laminate at one or more of the remaining lay-up stations.
Such a machine enables several laminates such as top and bottom wing skins to be produced on a single machine and is of considerable advantage in that respect.
Means may be provided for positioning the piece of fabric, which may be in the form of a sheet, at the forming station. The forming station may comprise a table on which the piece of fabric is placed and the table may include retention means and/or release means for the fabric. Conveniently, retention means may include the provision for applying vacuum to the surface of the fabric lying on the table to suck the fabric into firm contact with the table. To release the fabric, the vacuum may be released and a positive pressure applied to the said surface of the fabric. Where the fabric is an uncured fibre reinforced plastics, it may have a sticky surface which will tend to adhere to the table and the application of positive air pressure is useful in ensuring that it will be fully released when required.
The profiling means may comprise a beam of laser light or other suitable cutter which preferably cuts the fabric so as to leave a peripheral length of waste. A single length of waste may be formed such as a ring of waste material around a predetermined cut shape. A suitable removal means may be provided for removing the waste and may take the form of a rotary member such as a wheel or roll. Conveniently, vacuum may be applied to retain the cut piece of fabric in place while the scrap is being removed. The aforesaid removal means may serve a dual purpose. In that respect, it may be used to draw the piece of fabric on to the forming station as well as being used to remove the scrap after the fabric has been cut.
The aforesaid carrier means may comprise an elongate roller. The shaped formed fabric may also be elongate and may be picked up by the roller so as to lie around the periphery of the roller and extend longitudinally thereof. The roller can then take the elongate section of fabric from the forming station and deposit the fabric at the selected lay-up station. The roller then returns to the forming station to pick up the next piece of formed fabric for delivery to the previous or a further lay-up station. The roller may be divided into axial segments which can be subjected to air pressure, e.g. vacuum. The roller can be applied to the cut fabric at the forming station and vacuum applied to the roller thereby causing the cut fabric to adhere to the surface of the roller. Once the roller has taken the fabric to a lay-up station, positive pressure can then be applied in order to ensure that the fabric detaches from the surface of the roller for placement at the lay-up station.
The roller may also be divided circumferentially into a plurality of sectors and the sectors may house a foam or foam like material which provides a flexible periphery for the roller. Peripheral surfaces of the foam may be protected by a layer of film which may be perforated.
The roller may be mounted on adjustable mountings which will permit the outer tube of the roller to be varied. e.g. for pitch, yaw and for axial movement.
In order to ensure that the fabric is laid up accurately, position sensing means may be provided for the carrier means so that the position of the carrier means relative to a set datum can be determined. In that way, the position of the formed fabric oil the carrier means can be determined relative to the datum and, in that way, accurate placement of the fabric at the selected lay-up station can be ensured. The or a further position sensing means may be provided for sensing the position of the profiling means relative to the same or another datum.
Four lay-up stations may be provided which are adapted to receive shaped fabrics for laying up the respective upper and lower skins for port and starboard aerofoils such as the wings of an aircraft. The profiling means may be programmed to cut left and right hand shapes for the various wing skins.
The skins may be formed by laying a plurality of elongate skin sections edge-to-edge to form a further layer and by laying additional elongate skin sections edge-to-edge to form one or more further layers upon the first layer. In such a case, the edges of the skin sections of one layer are preferably staggered in relation to the edges of the skin sections of an adjacent layer of the laminate.